package logmower

import (
	"time"

	"github.com/jtagcat/util"
	prom "github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
	"go.mongodb.org/mongo-driver/bson"
	"go.uber.org/zap"
)

var (
	promShipperMongoSent = promauto.NewCounter(prom.CounterOpts{
		Subsystem: "shipper",
		Name:      "sent_count",
		Help:      "Log items successfully committed to mongo",
	})
	promShipperMongoSentError = promauto.NewCounter(prom.CounterOpts{
		Subsystem: "shipper",
		Name:      "mongo_errors",
		Help:      "Errors while submitting to mongo", // TODO:
	})
	promShipperDropped = promauto.NewCounterVec(prom.CounterOpts{
		Subsystem: "shipper",
		Name:      "queue_dropped",
		Help:      "Items ready to be sent to mongo, but dropped due to full queue",
	}, []string{"filename"})
)

func init() {
	promauto.NewGaugeFunc(prom.GaugeOpts{
		Subsystem: "shipper",
		Name:      "queue_size",
		Help:      "Submit queue size",
	}, func() float64 {
		return float64(SendQueueLimit)
	})
}

func (s *submitter) sender() {
	promauto.NewGaugeFunc(prom.GaugeOpts{
		Subsystem: "shipper",
		Name:      "queue_items",
		Help:      "Items in queue to be submitted in batch to mongo",
	}, func() float64 {
		return float64(len(s.sendQueue))
	})

	batched := make(chan []mLog)

	go func() {
		util.Batch(4, MaxBatchTime, s.sendQueue, batched)
	}()

	for {
		batch, ok := <-batched
		if !ok {
			return
		}

		var batchBson []interface{} // mongo does not like typing
		for _, b := range batch {
			batchBson = append(batchBson, b.toBson())
		}

		result, err := s.db.InsertMany(mongoTimeoutCtx(s.ctx), batchBson, nil)
		promShipperMongoSent.Add(float64(
			len(result.InsertedIDs)))

		if err != nil {
			s.l.Error("mongo send returned error; TODO: add some selective retry here or something", zap.Error(err)) // TODO:
		}
	}
}

// when editing, also edit toBson(); all bson.D (and bson.M) uses
type mLog struct {
	HostInfo HostInfo
	Filename string
	Offset   int64  // byte offset where log entry ends at
	Content  string // TODO:
	Time     time.Time
}

// not using marshal, since it is <0.1x performance
func (l *mLog) toBson() bson.M {
	return bson.M{
		"host_info": l.HostInfo,
		"filename":  l.Filename,
		"offset":    l.Offset,
		"content":   l.Content,
		"time":      l.Time,
	}
}